JP2589484Y2 - Electrolytic capacitor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the safety of an electrolytic capacitor, and more particularly to an electrolytic capacitor which is short-circuited to improve safety.

[0002]

2. Description of the Related Art When a reverse voltage or an excessive voltage is applied to an electrolytic capacitor, the internal pressure of the outer case rises, causing the electrolytic capacitor to burst. For this reason, ordinary electrolytic capacitors are provided with explosion-proof devices, and one of the representative ones is known to have a mechanically fragile part formed on an outer case or sealing plate called an explosion-proof valve. I have. This explosion-proof valve may be one in which a cutout groove is provided on the bottom or side surface of the outer case, or one in which rubber is inserted into a through hole of a sealing plate. In these explosion-proof valves, when the pressure in the outer case reaches a predetermined pressure, the rubber in the notch groove or the through-hole is split and the inner case pressure is released.

[0003]

[Problems to be solved by the invention] However, when the explosion-proof valve is opened, not only the unnecessary gas in the outer case is not exhausted, but also the electrolytic solution impregnated in the capacitor element and fragments of the capacitor element are unnecessary. At the same time as the gas was discharged, it could be scattered from the explosion-proof valve or rubber that had been torn.
If the electrolyte scattered on the substrate is exposed to a high temperature in the electric equipment, it may cause a fire or the like.

[0004] In order to solve such disadvantages, an electrolytic capacitor as disclosed in Japanese Patent Application Laid-Open No. 56-73421 has been proposed. The proposed electrolytic capacitor is
Make a hole in either the metal foil of the anode foil or the cathode foil of the capacitor element, and also make a hole in the separator where the hole of the metal foil comes in contact, and insert a hole between the hole of the metal foil and the hole of the separator. It is formed by disposing a thermoplastic resin film. In this electrolytic capacitor, when the temperature inside the electrolytic capacitor becomes high, the thermoplastic resin film melts and the anode foil and the cathode foil come into contact with each other to cause a short circuit. At this time, a large current caused by a short circuit is supplied to a protection device such as a fuse or a breaker provided in an external circuit, and the electrolytic capacitor is electrically cut off from the outside to ensure the safety of the electrolytic capacitor.

In such an electrolytic capacitor, although the contents of the outer case can be prevented from being scattered, which is a drawback of the explosion-proof valve, the structure of the ordinary capacitor element must be changed. Inevitably, a rise in manufacturing costs is inevitable. In addition, the point slightly away from the center of the capacitor element on which the proposed thermoplastic resin film is arranged, when an abnormal voltage is applied to the electrolytic capacitor, it is relatively gentle compared to the core. It is about to generate heat. For this reason, there is a possibility that the response to the abnormal temperature in the outer case of the thermoplastic resin film may be delayed, and sufficient reliability cannot be obtained.

An object of the present invention is to provide an electrolytic capacitor having a simple structure in which an electric function is quickly stopped when an abnormality occurs.

[0007]

According to the present invention, an elongated foil is attached to a hollow core portion of a capacitor element formed by laminating an anode foil, a separator and a cathode foil, and winding the same into a cylindrical shape. It is characterized in that a deformable shape memory alloy is arranged.

[0008]

When the temperature inside the outer case of the electrolytic capacitor of the present invention reaches a predetermined temperature, the elongated deformable shape memory alloy disposed in the hollow core portion of the capacitor element is deformed. At the same time, it penetrates into the inside of the capacitor element 1, and a through hole 12 is made in a layer of the capacitor element 1 including the anode foil 2, the separator 4 and the cathode foil 3. At this time, the shape memory alloy 11 pierced into the inside of the capacitor element 1 causes the anode foil 2 and the cathode foil 3 around the shape memory alloy 11 to burr.
At the same time, the burr 13 of the anode foil 2 is brought into contact with the burr 13 of the cathode foil 3 to bring the electrolytic capacitor into a short-circuit state. When a protection device such as a fuse is provided in series with the external terminal 8 of the electrolytic capacitor, a large current caused by a short circuit of the electrolytic capacitor activates the protection device to cut off the electrolytic capacitor from the external circuit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an electrolytic capacitor according to an embodiment of the present invention. FIG. 2 is a sectional view of the electrolytic capacitor showing a state where the shape memory alloy of FIG. 1 is deformed. FIG. 3 is a partially enlarged sectional view of FIG.

A capacitor element 1 shown in FIG. 1 is laminated by stacking a separator 4 between an anode foil 2 and a cathode foil 3 made of a valve metal such as aluminum, and the winding core of the capacitor element winding machine. After being wound tightly in a cylindrical shape with a rod or the like, the core rod is pulled out and formed. At the center of the capacitor element 1, a hollow core portion 5 is formed at the mark where the winding core rod is pulled out. An electrode tab 6 connected to the anode foil 2 and the cathode foil 3 is led out from one end face of the capacitor element 1.

A bottomed cylindrical outer case 7 made of aluminum houses the capacitor element 1 impregnated with an electrolytic solution, and the opening end side thereof is sealed with a sealing plate 9 by drawing and curling. .

A rivet 10 is mounted on a sealing plate 9 made of a synthetic resin having a hard rubber adhered to the surface, and the electrode tab 6 and the external terminal 8 are electrically connected via the rivet 10. I have.

The hollow core portion 5 of the capacitor element 1 has a cylindrical shape memory having substantially the same diameter as the core portion 5 and having a length substantially equal to the long axis direction of the capacitor element 1. Alloy 11 is arranged. Of course, the shape memory alloy 11 stored in the core part 5 is not limited to a cylindrical shape, but may be any long shape. For example, a rod shape, a needle shape, a prism, a plate shape, and the like can be given. Further, the diameter of the shape memory alloy 11 is not substantially the same as the diameter of the core part 5 and may be smaller.

As shown in FIG. 2, when the shape memory alloy 11 reaches a predetermined temperature, the shape memory alloy 11 is stored in advance so as to be deformed into an S-shape, and then placed on the core 5. Of course, the shape of the shape memory alloy 11 after deformation is not limited to this, and any shape may be used as long as it deforms so as to bite into the inside of the capacitor element 1 such as, for example, a U-shaped shape.

The predetermined temperature is a temperature at which the shape memory alloy 11 starts to deform. The deformation start temperature of the shape memory alloy 11 is preferably set to a temperature higher than the upper limit of the operating temperature range of the electrolytic capacitor. The predetermined temperature can be appropriately set according to the purpose of use of the electrolytic capacitor, the heat resistance of the constituent materials, and the like.
It is desirable to be in the range of 0 ° C to 250 ° C.

As described above, in this embodiment, FIGS.
As shown in the figure, when the inside of the outer case 7 of the electrolytic capacitor reaches a predetermined temperature, the cylindrical shape memory alloy 11 which is arranged in the hollow core portion 5 of the capacitor element 1 and which is deformed into an S shape is While being deformed, it penetrates into the tightly wound capacitor element 1, and a through hole 12 is made in a layer of the capacitor element 1 including the anode foil 2, the separator 4 and the cathode foil 3. At this time, the shape memory alloy 11 pierced inside the capacitor element 1
The burr 13 is generated on the anode foil 2 and the burr 13 on the anode foil 2 at the same time as the burr 13 is brought into contact with the burr 13 on the cathode foil 3 to bring the electrolytic capacitor into a short-circuit state. At this time, if a protection device such as a fuse is provided in series with the external terminal 8 of the electrolytic capacitor, a large current due to the short circuit of the electrolytic capacitor activates the protection device to cut off the electrolytic capacitor from the external circuit.

Further, the shape memory alloy 11 of the present embodiment has substantially the same diameter as the core portion 5 and has substantially the same length as the long axis direction of the capacitor element 1. Also plays the role of the core of the element 1 and the capacitor element 1
Can be prevented from becoming loose.

Further, in the present embodiment, a cylindrical capacitor element has been described as an example, but the capacitor element may be formed in an elliptical cylindrical shape without impeding the present invention. In this case, both the outer case and the sealing plate are suitable for the external shape of the capacitor element.

The shape memory alloy 11 of the present embodiment includes:
Although a cylindrical shape is used, the shape is not limited to this. For example, the end of a cylindrical shape memory alloy may be formed in a conical shape and the tip may be sharpened. In this case, as compared with the cylindrical shape memory alloy of the present embodiment, it becomes easier to bite into the capacitor element.

[0020]

As described above, according to the present invention, an anode foil, a separator, and a cathode foil are laminated, and a hollow core portion of a capacitor element formed by winding into a cylindrical shape is provided with an elongated shape. A deformable shape memory alloy is arranged. For this reason, when an abnormal voltage or the like is applied to the electrolytic capacitor and the inside of the electrolytic capacitor reaches a predetermined temperature, the shape memory alloy is deformed and bites into the capacitor element, and at the same time, the anode foil and the cathode foil come into contact with each other. Then, the electrolytic capacitor is short-circuited. At this time, if a protective device such as a fuse is installed in series with the external terminal of the electrolytic capacitor, a large current due to a short circuit will activate the protective device to cut off the electrolytic capacitor from the external circuit, and the electrical function of the electrolytic capacitor Is stopped immediately to suppress generation of gas in the outer case. Therefore, there is no scattering of the contents of the outer case due to the opening of the explosion-proof valve as in the past,
The safety of the electrolytic capacitor is improved.

The core of the capacitor element on which the rod-shaped shape memory alloy is disposed is formed by using a core which is formed due to its structure when a normal cylindrical capacitor element is wound and formed. Therefore, the safety of the electrolytic capacitor can be achieved with a very simple structure without any change in the structure of the electrolytic capacitor.

In addition, since the structure of the ordinary electrolytic capacitor is not changed, the conventional electrolytic capacitor manufacturing equipment can be used as it is, and an increase in the manufacturing cost can be suppressed.

Further, when an abnormal voltage or the like is applied to the electrolytic capacitor, the winding core on which the shape memory alloy is disposed
Since it is the hottest place in the electrolytic capacitor, the shape memory alloy can quickly sense abnormal temperatures,
The reliability of the electrolytic capacitor is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the electrolytic capacitor when the shape memory alloy according to the embodiment of the present invention is deformed.

FIG. 3 is a partially enlarged sectional view of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode foil 3 Cathode foil 4 Separator 5 Core part 6 Electrode tab 7 Outer case 8 External terminal 9 Sealing plate 10 Rivet 11 Shape memory alloy 12 Through hole 13 Burr

Claims (1)

(57) [Scope of request for utility model registration] An elongated deformable shape memory alloy is disposed on a hollow core portion of a capacitor element formed by laminating an anode foil, a separator, and a cathode foil, and winding the resultant into a cylindrical shape. An electrolytic capacitor characterized by the following.